Wireless access node fault recovery using integrated access and backhaul

ABSTRACT

In a wireless access node, a baseband unit (BBU) detects a fault and responsively directs an Integrated Access and Backhaul (IAB) Mobile Terminal (MT) to scan for a wireless IAB service. The IAB MT scans for the wireless IAB service and establishes a wireless IAB link. The BBU exchanges fault data with the IAB MT. The IAB MT wirelessly exchanges the fault data with a neighbor access node over the wireless IAB link. The BBU recovers from the fault in response to the fault data.

TECHNICAL BACKGROUND

Wireless communication networks provide wireless data services towireless user devices. Exemplary wireless data services includemachine-control, internet-access, media-streaming, andsocial-networking. Exemplary wireless user devices comprise phones,computers, vehicles, robots, and sensors. The wireless communicationnetworks have wireless access nodes that exchange wireless signals withthe wireless user devices using wireless network protocols. Exemplarywireless network protocols include Institute of Electrical andElectronic Engineers (IEEE) 802.11 (WIFI), Long Term Evolution (LTE),Fifth Generation New Radio (5GNR), and Low-Power Wide Area Network(LP-WAN).

The wireless access nodes are coupled to the wireless communicationnetworks over backhaul links. The backhaul links use data communicationprotocols like Time Division Multiplex (TDM), IEEE 802.3 (ethernet),Internet Protocol (IP), and the like. The backhaul links typically usephysical media like metal or glass. To extend the range of theirwireless data services, the wireless communication networks aredeploying wireless backhaul links. The wireless backhaul links usewireless network protocols like WIFI, LTE, and 5GNR. The ThirdGeneration Partnership Project (3GPP) Technical Report (TR) 38.874describes wireless Integrated Access and Backhaul (IAB) for wirelesscommunication networks. 3GPP TR 38.874 specifies the IAB Mobile Terminal(MT) that provides wireless connectivity to a wireless access node overa wireless backhaul link. The IAB MT may be configured and operate likea wireless user device, but the IAB MT serves a wireless access node andnot an end-user.

Unfortunately, wireless access nodes experience network faults thatdegrade or terminate their wireless data services. For example, an IProuter or ethernet switch in a wireless access node may crash and becomenon-responsive. IAB describes techniques to discover and use alternativewireless backhaul links to bypass these faults. Technicians andtroubleshooting systems are then used to fix the bypassed fault. IAB andthe IAB Mobile Terminal (MTs) have not been efficiently and effectivelyused by wireless access nodes and wireless communication networks to fixthese types of network faults.

TECHNICAL OVERVIEW

In a wireless access node, a baseband unit (BBU) detects a fault andresponsively directs an Integrated Access and Backhaul (IAB) MobileTerminal (MT) to scan for a wireless IAB service. The IAB MT scans forthe wireless IAB service and establishes a wireless IAB link. The BBUexchanges fault data with the IAB MT. The IAB MT wirelessly exchangesthe fault data with a neighbor access node over the wireless IAB link.The BBU recovers from the fault in response to the fault data.

DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication network that uses IntegratedAccess and Backhaul (IAB) to recover from wireless access node faults.

FIG. 2 illustrates the operation of the wireless communication networkto use IAB to recover from wireless access node faults.

FIG. 3 illustrates the operation of the wireless communication networkto use IAB to recover from wireless access node faults.

FIG. 4 illustrates a Fifth Generation New Radio (5GNR) access node in aFifth Generation (5G) wireless network that uses IAB to recover from5GNR access node faults.

FIG. 5 illustrates a 5GNR User Equipment (UE) in the 5G wirelessnetwork.

FIG. 6 illustrates a 5G Core NFVI in the 5G wireless network.

FIG. 7 illustrates the operation of the 5G wireless network to use IABto recover from 5GNR access node faults.

FIG. 8 illustrates another 5GNR access node in another 5G wirelessnetwork that uses IAB to recover from 5GNR access node faults.

FIG. 9 illustrates the operation of the other 5G wireless network to useIAB to recover from 5GNR access node faults.

DETAILED DESCRIPTION

FIG. 1 illustrates wireless communication network 100 that usesIntegrated Access and Backhaul (IAB) to recover from wireless accessnode faults. Wireless communication network 100 comprises User Equipment(UEs) 101-106, wireless access node 111, neighbor access node 112,signaling element 121, data element 122, and network controller 123.Wireless communication network 100 serves UE 103-106 with wireless dataservices like internet-access, messaging, conferencing, machine control,or some other wireless networking product. UEs 101-103 might be phones,computers, robots, vehicles, or some other data appliances with wirelesscommunication circuitry.

UEs 101-103 and wireless access node 111 are coupled over wireless links131. UEs 104-106 and neighbor access node 112 are coupled over wirelesslinks 132. To recover from faults, wireless access node 111 and neighboraccess node 112 are coupled over wireless IAB link 133. Links 131-133use Fifth Generation New Radio (5GNR), Long Term Evolution (LTE), IEEE802.11 (WIFI), Low-Power Wide Area Network (LP-WAN), or some otherwireless communication protocol. Links 131-133 use electromagneticfrequencies in the low-band, mid-band, high-band, or some other part ofthe electromagnetic spectrum.

Wireless access node 111 and signaling element 121 are coupled overbackhaul link 141. Wireless access node 111 and data element 122 arecoupled over backhaul link 142. Neighbor access node 112 and signalingelement 121 are coupled over backhaul link 143. Neighbor access node 112and data element 122 are coupled over backhaul link 144. Signalingelement 121 is coupled to external systems over data link 145. Dataelement 122 is coupled to external systems over data link 146. Signalingelement 121 and data element 122 are coupled over network link 147.Signaling element 121 and network controller 123 are coupled overnetwork link 148. Data element 122 and network controller 123 arecoupled over network link 149. Links 141-144 use Institute of Electricaland Electronic Engineers (IEEE) 802.3 (Ethernet), Time DivisionMultiplex (TDM), Data Over Cable System Interface Specification(DOCSIS), Internet Protocol (IP), 5GNR, WIFI, LTE, LP-WAN, or some otherdata communication protocol. Links 145-146 use TDM, Ethernet, IP, 5GNRor some other data communication protocol. Links 147-149 use TDM,Ethernet, IP, 5GNR, virtual switching, inter-processor communications,or some other data communication protocol.

Access nodes 111-112 comprise radio circuitry and Baseband Unit (BBU)circuitry. The radio circuitry comprises antennas, filters, amplifiers,analog-to-digital interfaces, microprocessors, memory, software,transceivers, bus circuitry, and the like. The BBU circuitry comprisesmicroprocessors, memory, software, transceivers, and bus circuitry, andthe like. The microprocessors comprise Digital Signal Processors (DSP),Central Processing Units (CPUs), Graphical Processing Units (GPUs),Application-Specific Integrated Circuits (ASICs), and/or the like. Thememories comprise Random Access Memory (RAM), flash circuitry, diskdrives, and/or the like. The memories store software like operatingsystems and network applications.

Signaling element 121, data element 122, and network controller 123comprise processing circuitry like microprocessors, memory, software,transceivers, and bus circuitry. The microprocessors comprise CPU, GPUs,ASICs, and/or the like. The memories comprise RAM, flash circuitry, diskdrives, and/or the like. The memories store software like operatingsystems, virtual layers, and network applications. Signaling element 121comprises an Access and Mobility Management Function (AMF), SessionManagement Function (SMF), Mobility Management Entity (MME),Software-Defined Network (SDN) controller, or some other control-planeprocessor. Data element 122 comprises a User Plane Function (UPF),Serving Gateway (SGW), Packet Data Network Gateway (PGW), SDN packetprocessor, or some other data-plane machine. Network controller 123comprises a Technical Assistance Center (TAC), Fault Management System(FMS), or some other fault recovery computer system.

The BBU circuitry in wireless access node 111 exchanges networksignaling with signaling element 121 over backhaul link 141. Signalingelement 121 exchanges network signaling with data element 122 overnetwork link 147. In response to the network signaling. The radiocircuitry in wireless access node 111 wirelessly exchanges user datawith UEs 101-103 over links 131. The radio circuitry and the BBUcircuitry in wireless access node 111 exchange the user data. The BBUcircuitry in wireless access node 111 exchanges the user data with dataelement 122 over backhaul link 142. Data element 122 exchanges the userdata with other systems over data link 146.

Neighbor access node 112 exchanges network signaling with signalingelement 121 over backhaul link 143. Signaling element 121 exchangesnetwork signaling with data element 122 over network link 147. Inresponse to the network signaling, neighbor access node 112 wirelesslyexchanges user data with UEs 104-106 over links 132. Neighbor accessnode 112 exchanges the user data with data element 122 over backhaullink 144. Data element 122 exchanges the user data with other systemsover data link 146.

A fault occurs in wireless access node 111 that inhibits backhaulcommunications. For example, a cell-site router or ethernet switch inwireless access node 111 may crash. Wireless access node 111 detects thefault, and in response, the radio circuitry scans for wireless IABservice. Typically, the BBU circuitry in wireless access node 111initially detects the fault by sensing a loss of communications overbackhaul links 141-142.

Signaling element 121 and/or data element 122 detect the fault andresponsively transfer fault information to network controller 123.Typically, elements 121-122 initially detect the fault by sensing a lossof communications over backhaul links 141-142. Network controller 123detects the fault in response to the fault information and selectsneighbor access node 112 to help with fault recovery. For example,network controller 123 might host a data structure that translates acommunication loss with wireless access node 111 into the ID forneighbor node 112. Network controller 123 may process network topologydata and access node status to select neighbor access node 112 based onits physical proximity to wireless access node 111 and based on normaloperational status for backhaul links 143-144.

Network controller 123 transfers network signaling to neighbor accessnode 112 to initiate wireless IAB service over elements 121-122 andbackhaul links 143-144. In response to the signaling, neighbor accessnode 112 wirelessly transmits an IAB broadcast to identify its IABservice. The radio circuitry in wireless access node 111 is scanning forand receives the IAB broadcast. In response to receiving the IABbroadcast, the radio circuitry in wireless access node 111 exchanges IABattachment signaling with neighbor access node 112 to establish wirelessIAB link 133.

Wireless access node 111 and/or neighbor access node 112 report IAB link133 to network controller 123 over elements 121-122 and backhaul links143-144. Network controller 123 and the BBU circuitry in wireless accessnode 111 exchange fault data to perform fault recovery. The exchange ofthe fault data occurs over wireless IAB link 133, neighbor access node112, backhaul link 143 or 144, element 121 or 122, and network link 148or 149.

Wireless access node 111 recovers from the fault in response to thefault data. For example, the BBU circuitry in wireless access node 111may reboot a hardware component and/or a software component responsiveto the signaling. The hardware/software components may reside incell-site routers, ethernet switches, or some other access nodecircuitry.

After the fault recovery, the BBU circuitry in wireless access node 111exchanges network signaling with signaling element 121 over backhaullink 141. Signaling element 121 exchanges network signaling with dataelement 122 over network link 147. In response to the network signaling,the radio circuitry in wireless access node 111 wirelessly exchangesuser data with UEs 101-103 over links 131. The radio circuitry exchangesthe user data with the BBU circuitry in wireless access node 111. TheBBU circuitry in wireless access node 111 exchanges the user data withdata element 122 over backhaul link 142. Data element 122 exchanges theuser data with other systems over data link 146.

Advantageously, wireless communication network 100 efficiently andeffectively uses IAB to fix network faults at wireless access node 111.

In some examples, wireless access node 111 comprises an IAB MobileTerminal (MT). The IAB MT is similar to UEs 101-106 but the IAB MT isadapted to serve IAB link 133 to wireless access node 111. In theseexamples, the BBU circuitry in wireless access node 111 directs the IABMT to scan for the wireless IAB service in response to the fault. TheIAB MT processes a stored list of IAB frequencies to scan thefrequencies and detect an IAB broadcast from neighbor access node 112 atone of the IAB frequencies. The IAB MT attaches to the wireless IABservice responsive to the IAB broadcast. The BBU circuitry in wirelessaccess node then exchanges fault data with network controller 123 overthe IAB MT, IAB link 133, neighbor access node 112, backhaul link143/144, element 121/122, and network link 148/149.

In other examples, the radio circuitry in wireless access node 111 thatserves UEs 101-103 over wireless links 131 also handles IAB link 133.The radio circuitry scans for the wireless IAB service in response toBBU instructions for the fault. The radio circuitry attaches to thewireless IAB service responsive to the IAB broadcast. The BBU circuitryin wireless access node 111 then exchanges fault data with networkcontroller 123 over the radio circuitry, IAB link 133, neighbor accessnode 112, backhaul link 143/144, element 121/122, and network link148/149.

FIG. 2 illustrates the operation of wireless communication system 100 touse IAB to recover from wireless access node faults. Wireless accessnode 111 wirelessly exchanges user data with UEs 101-103 and exchangesthe user data with wireless communication network 100 (201). Wirelessaccess node 111 monitors for faults (201). When wireless access node 111detects a fault (202), wireless access node 111 scans for a wireless IABservice (203). Wireless access node 111 wirelessly exchanges fault datawith neighbor access node 112 over IAB link 133 (204). Wireless accessnode 111 recovers from the fault in response to the fault data (205).After fault recovery, the operation in wireless access node 111 repeats(201).

Contemporaneously with operations 201-205, network controller 123monitors for faults (206). When network controller 123 detects the fault(207), network controller 123 transfers network signaling to neighboraccess node 112 to initiate the wireless IAB service (208). Neighboraccess node 112 wirelessly exchanges the fault data with wireless accessnode 111 over IAB link 133 (209). Neighbor access node 112 exchanges thefault data with network controller (210). The contemporaneous operationthen repeats (206).

FIG. 3 illustrates the operation of the wireless communication system100 to use IAB to recover from wireless access node faults. UEs 101-103and wireless access node 111 wirelessly exchange user data. Wirelessaccess node 111 exchanges the user data with data element 122. Dataelement 122 exchanges the user data with other systems. Wireless accessnode 111 detects a fault and responsively scans for wireless IABservice.

Signaling element 121 or data element 122 also detect the fault andresponsively transfer fault information to network controller 123.Network controller 123 selects neighbor access node 112 to help withfault recovery based on the fault information. Network controller 123transfers network signaling to establish the IAB link to signalingelement 121. Signaling element 121 transfers network signaling toestablish the IAB link to neighbor access node 112. In response to thenetwork signaling, neighbor access node 112 wirelessly transmits an IABbroadcast to identify its IAB service—typically on a short and periodicbasis. Wireless access node 111 scans and receives the IAB broadcast. Inresponse to receiving the IAB broadcast, wireless access node 111 andneighbor access node 112 exchange IAB attachment signaling to establishwireless IAB link 133.

Wireless access node 111 and network controller 123 exchange fault dataover IAB link 133 served by neighbor access node 112. Wireless accessnode 111 recovers from the fault in response to the fault data. Afterthe fault recovery, UEs 101-103 wirelessly exchange user data withwireless access node 111. Wireless access node 111 exchanges the userdata with data element 122. Data element 122 exchanges the user datawith other systems.

FIG. 4 illustrates Fifth Generation New Radio (5GNR) access node 411 inFifth Generation (5G) wireless network 400 that uses IAB to recover from5GNR access node faults. 5G network 400 is an example of wirelesscommunication network 100, although network 100 may differ. 5G network400 comprises UE 401, 5GNR access nodes 411-412, and 5G core NetworkFunction Virtualization Infrastructure (NFVI) 420. 5GNR access node 411is an example of access nodes 111-112, although access nodes 111-112 maydiffer.

5GNR access node 411 comprises Distributed Unit (DU) 460, ethernetswitch (ENET SW) 466, Internet Protocol router (IP RTR) 467, andCentralized Unit (CU) 470. DU 460 comprises radio circuitry 461, memory462, CPU 463, DU XCVR 464, and IAB Mobile Terminal (MT) 465 that arecoupled over bus circuitry. XCVR refers to transceiver. Radio circuitry461 comprises antennas, amplifiers (AMPS), filters, modulation,analog-to-digital interfaces, DSP, and memory that are coupled over buscircuitry. CU 470 comprises CU XCVR 471, memory 472, CPU 473, and IAB MT474 that are coupled over bus circuitry.

5GNR access node 411 comprises radio circuitry 461 and BBU circuitry413. BBU circuitry 413 comprises CU 470, Ethernet switch 466, IP router467, and a portion of DU 460 (memory 462, CPU 463, DU XCVR 464, IAB MT465, and associated bus circuitry). UE 401 is wirelessly coupled to theantennas in DU 460. DU XCVR 464 is coupled to ethernet switch 466.Ethernet switch 466 is coupled to IP router 467 and CU XCVR 471. IProuter 467 is coupled to 5G core NFVI 420. IAB MTs 465 and 474 can bewirelessly linked to 5GNR access node 412 using IAB.

In DU 460, memory 462 stores operating system (OS), Physical Layer(PHY), Media Access Control (MAC), Radio Link Control (RLC), and faultrecovery application (FAULT). In CU 470, memory 472 stores an operatingsystem, virtual layer (VL), Packet Data Convergence Protocol (PDCP),Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP),and fault recovery application. The virtual layer comprises hypervisormodules, virtual switches, virtual CPUs, and/or the like. CPU 473 in CU470 executes the PDCP, RRC, and SDAP to drive the exchange of user dataand network signaling between 5G core NFVI 420 and DU 460—includingfault detection. CPU 463 in DU 460 executes the PHY, MAC, and RLC todrive the transfer of user data and network signaling between CU 470 andUE 401—including fault detection. The functionality split of the networkapplications (PHY, MAC, RLC, PDCP, RRC, SDAP) between DU 460 and CU 470may vary.

In radio circuitry 461 of DU 460, the antennas receive wireless 5GNRsignals from 5GNR UE 401 that transport the Uplink (UL) signaling anddata. The antennas transfer corresponding electrical UL signals throughduplexers to the amplifiers. The amplifiers boost the received ULsignals for filters which attenuate unwanted energy. In modulation,demodulators down-convert the UL signals from their carrier frequency.The analog/digital interfaces convert the analog UL signals into digitalUL signals for the DSP. The DSP recovers UL 5GNR symbols from the ULdigital signals. In DU 460 and CU 470, CPU 463 and CPU 473 execute thenetwork applications to process the UL 5GNR symbols and recover the ULsignaling and data. In CU 470, CPU 473 executes the RRC to generatecorresponding UL N2 signaling and UL N3 data. CU 470 transfers the UL N2signaling to Access and Mobility Management Functions (AMFs) in 5G coreNFVI 420 over ethernet switch 466 and IP router 467. CU 470 transfersthe UL N3 data to User Plane Functions (UPFs) in 5G core NFVI 420 overethernet switch 466 and IP router 467.

In CU 470, CU XCVR 471 receives Downlink (DL) N2 signaling from the AMFsand DL N3 data from the UPFs in 5G core NFVI 420 over ethernet switch466 and IP router 467. In CU 470 and DU 460, CPU 473 and 463 execute thenetwork applications to generate corresponding DL signaling and data. InCU 470 and DU 460, CPU 473 and CPU 463 execute the network applicationsto process the DL signaling and data to generate DL 5GNR symbols thatcarry the DL signaling and data. In DU 460, the DSP processes the DL5GNR symbols to generate corresponding digital signals for theanalog-to-digital interfaces. The analog-to-digital interfaces convertthe digital DL signals into analog DL signals for modulation. Modulationup-converts the DL signals to their carrier frequency. The amplifiersboost the modulated DL signals for the filters which attenuate unwantedout-of-band energy. The filters transfer the filtered DL signals throughduplexers to the antennas. The electrical DL signals drive the antennasto emit corresponding wireless 5GNR signals that transport the DLsignaling and data to 5GNR UE 401.

RRC functions comprise authentication, security, handover control,status reporting, Quality-of-Service (QoS), network broadcasts andpages, and network selection. SDAP functions comprise QoS marking andflow control. PDCP functions comprise LTE/5GNR allocations, securityciphering, header compression and decompression, sequence numbering andre-sequencing, de-duplication. RLC functions comprise Automatic RepeatRequest (ARQ), sequence numbering and resequencing, segmentation andresegmentation. MAC functions comprise buffer status, power control,channel quality, Hybrid Automatic Repeat Request (HARM), useridentification, random access, user scheduling, and QoS. PHY functionscomprise packet formation/deformation, windowing/de-windowing,guard-insertion/guard-deletion, parsing/de-parsing, controlinsertion/removal, interleaving/de-interleaving, Forward ErrorCorrection (FEC) encoding/decoding, rate matching/de-matching,scrambling/descrambling, modulation mapping/de-mapping, channelestimation/equalization, Fast Fourier Transforms (FFTs)/Inverse FFTs(IFFTs), channel coding/decoding, layer mapping/de-mapping, precoding,Discrete Fourier Transforms (DFTs)/Inverse DFTs (IDFTs), and ResourceElement (RE) mapping/de-mapping.

A fault occurs in 5GNR access node 411. For example, ethernet switch 466or IP router 467 may fail. The RRC and/or SDAP in CU 470 detect thefault by sensing the loss of N2 signaling or N3 data and notifying thefault recovery application in CU 470 or DU 460. In response to thefault, the fault recovery application in CU 470 and/or CU 460 directsIAB MT 474 and/or IAB MT 465 to scan for wireless IAB service. IAB MT474 and/or 465 host a list of IAB frequencies to scan and eventuallydetect an IAB broadcast. In response to detecting the IAB broadcast, IABMT 465 and/or IAB MT 474 wirelessly exchange IAB attachment signalingwith 5GNR access node 512 and establish a wireless IAB link.

The fault recovery application and a network controller in 5G core NFVI420 exchange fault data to perform fault recovery. The exchange of thefault data occurs over the wireless IAB link. The fault recoveryapplication recovers from the fault in response to the fault dataexchange with 5G core NFVI 420. The fault recovery application mayreboot ethernet switch 466, IP router 467, radio circuitry 461, or theirrespective software components. After fault recovery, CPU 473 in CU 470executes the PDCP, RRC, and SDAP to drive the exchange of user data andnetwork signaling between 5G core NFVI 420 and DU 460—including faultdetection. CPU 463 in DU 460 executes the PHY, MAC, and RLC to drive thetransfer of user data and network signaling between CU 470 and UE401—including fault detection.

FIG. 5 illustrates 5GNR UE 401 in 5G wireless network 400. 5GNR UE 401is an example of UEs 101-106, although UEs 101-106 may differ. 5GNR UE401 is similar to MTs 465 and 474. UE 401 comprises radio circuitry 581,user interfaces 582, CPU 583, and memory 484 which are interconnectedover bus circuitry. Radio circuitry 581 comprises antennas, amplifiers,filters, modulation, analog-to-digital interfaces, DSP, and memory thatare coupled over bus circuitry. The antennas in 5GNR UE 401 are coupledto 5GNR access node 411. User interfaces 582 comprise graphic displays,machine controllers, sensors, cameras, transceivers, and/or some otheruser components. Memory 584 stores an operating system, userapplications, and network applications. The network applicationscomprise PHY, MAC, RLC, PDCP, RRC and SDAP. CPU 583 executes theoperating system, user applications, and network applications toexchange 5GNR signaling and data with 5GNR access node 411 over radiocircuitry 581.

FIG. 6 illustrates 5G Core NFVI 420 in 5G wireless network 400, whereNFVI refers to Network Function Virtualization Infrastructure. 5G coreNFVI 420 is an example of signaling element 121, data element 122, andnetwork controller 123, although elements 121-122 and controller 123 maydiffer. 5G core NFVI 420 comprises 5G hardware 621, 5G hardware drivers622, 5G operating systems and hypervisors 623, 5G virtual layer 624, and5G Virtual Network Functions (VNFs) 625. 5G hardware 621 comprisesNetwork Interface Cards (NICs), CPUs, RAM, flash/disk drives, and dataswitches (SWS). 5G virtual layer 624 comprises virtual NICs (vNIC),virtual CPUs (vCPU), virtual RAM (vRAM), virtual Drives (vDRIVE), andvirtual Switches (vSW). The NICs are coupled to 5GNR access nodes411-412 and external systems over data links. 5G VNFs 625 compriseAuthentication and Security Functions (AUSF), Policy Control Functions(PCF), Access and Mobility Management Functions (AMF), SessionManagement Functions (SMF), User Plane Functions (UPF), Unified DataManagement (UDM), Network Slice Selection Functions (NSSF), ApplicationFunctions (AF), and Network Controller Functions (NET CNT). Other 5Gnetwork functions are typically present but are omitted for clarity. 5Ghardware 621 executes 5G hardware drivers 622, 5G operating systems andhypervisors 623, 5G virtual layer 624, and 5G VNFs 625 to serve the 5GNRUE 401 with data services.

The UPF and AMF detect faults by sensing a loss of communication with5GNR access node 411. The UPF and AMF notify the NET CNT of the faultfor 5GNR access node 411. The NET CNT selects 5GNR access node 412 (andpossibly other access nodes) to start IAB service to fix the fault basedon proximity and status. The NET CNT signals 5GNR access node 412 overthe AMF or UPF to start IAB service for 5GNR access node 411 with a linkback to the NET CNT. The NET CNT exchanges fault data with 5GNR accessnode 411. The fault data from wireless access node 411 characterizes thefailing system like a crashed ethernet switch, unresponsive IP router,or noisy radio. The NET CNT identifies recovery actions or scripts basedon the fault characterization. The recovery actions or scripts maycomprise instructions to reboot hardware components by removing theirpower supply or rebooting software components by reinstalling them frommemory. The fault data sent to 5GNR access node 411 indicates therecovery actions or scripts.

FIG. 7 illustrates the operation of 5G wireless network 400 to use IABto recover from 5GNR access node faults. In 5GNR UE 401, the userapplication exchanges user data and signaling with the RRC/SDAP. TheRRC/SDAP in UE 401 exchanges corresponding network signaling with theRRC/SDAP in 5GNR access node 411 over their PDCPs, RLCs, MACs, and PHYs.The RRC exchanges N2 signaling with the AMF. The SDAP exchanges N3 datawith the UPF.

A fault occurs in 5GNR access node 411. The RRC/SDAP detect the fault bysensing the loss of N2 signaling or N3 data. The RRC/SDAP notify thefault recovery application. In response, the fault recovery applicationdirects an IAB MT (IAB) to establish an IAB link. The IAB MT configuresits RRC, SDAP, PDCP, RLC, MAC, and PHY to handle IAB attachment and IABlinks.

In 5G core NFVI 420, the UPF detects the fault by sensing a loss of N3data from 5GNR access node 411. The AMF detects the fault by sensing aloss of N2 signaling from 5GNR access node 411. The UPF and AMF notifythe NET CNT of the fault for 5GNR access node 411. The NET CNT selects5GNR access node 412 (and possibly other access nodes) to start IABservice based on proximity and status. The NET CNT signals an IABcontroller (IAB) in 5GNR access node 412 over the AMF or UPF to startIAB service for 5GNR access node 411 with a link back to the NET CNT.

The IAB controller in 5GNR access node 412 starts to broadcast IABinformation over the RRC, PDCP, RLC, MAC, and PHY. The IAB controller in5GNR access node 412 configures the RRC, SDAP, PDCP, RLC, MAC, and PHYto handle IAB attachment and IAB links over a portion of its wirelessspectrum. The IAB broadcast and configuration may cycle on and off, havea short on cycle, and use a narrow amount of bandwidth.

One of IAB MTs 466 and 474 in 5GNR node 411 detects the IAB broadcastfrom 5GNR access node 412 over its RRC, PDCP, RLC, MAC, and PHY. Thedetecting IAB MT in 5GNR node 411 exchanges IAB attachment signalingwith the IAB controller in 5GNR node 412 over their RRCs, PDCPs, RLCs,MACs, and PHYs. The IAB MT in 5GNR node 411 and the IAB controller in5GNR node 412 establish a wireless IAB link over their RRCs, SDAPs,PDCPs, RLCs, MACs, and PHYs. The IAB controller in 5GNR node 412 couplesthe IAB link to the NET CNT in 5G core NFVI 420 over the UPF or AMF.

The fault recovery application in 5GNR node 411 and the NET CNT in 5Gcore NFVI 420 exchange fault data to perform fault recovery. Theexchange of the fault data occurs over the IAB MT, the wireless IABlink, and 5GNR node 412. The fault recovery application recovers fromthe fault in response to the fault data exchange with the NET CNT in 5Gcore NFVI 420. After fault recovery, 5GNR access node 411 wirelesslyexchanges user data and signaling with 5GNR UE 401 and also exchanges N2signaling and N3 data with the AMF and UPF in 5G core NFVI 420.

FIG. 8 illustrates 5GNR access node 811 in 5G wireless network 800 thatuses IAB to recover from 5GNR access node faults. 5G network 800 is anexample of wireless communication network 100, although network 100 maydiffer. 5G network 800 comprises UE 801, 5GNR access nodes 811-812, and5G core NFVI 820. 5GNR access node 811 is an example of access nodes111-112, although access nodes 111-112 may differ. 5GNR access node 811comprises Distributed Unit (DU) 860, ethernet switch 865, IP router 866,and Centralized Unit (CU) 870. DU 860 comprises radio circuitry 861,memory 862, CPU 863, and DU XCVR 864 that are coupled over buscircuitry. Radio circuitry 861 comprises antennas, amplifiers, filters,modulation, analog-to-digital interfaces, DSP, and memory that arecoupled over bus circuitry. CU 870 comprises CU XCVR 871, memory 872,and CPU 873 that are coupled over bus circuitry. In 5GNR access node811, BBU circuitry 813 comprises CU 870, Ethernet switch 866, IP router867, and a portion of DU 860 (memory 862, CPU 863, DU XCVR 864, andassociated bus circuitry).

5GNR communication network 800 and 5GNR access node 811 operate like5GNR communication network 400 and 5GNR access node 411 except that 5GNRaccess node 811 uses radio circuitry 861 for wireless IAB serviceinstead of an IAB MT. In DU 860, memory 462 stores operating system,PHY, MAC, and RLC. In CU 870, memory 872 stores an operating system,virtual layer, PDCP, RRC, SDAP, fault recovery application, and IABcontroller. When a fault occurs in 5GNR access node 811, the faultrecovery application directs the IAB controller to use a portion ofradio circuitry 861 for wireless IAB service. The IAB controller mayhost a list of IAB frequencies to scan and detect an IAB broadcast. Inresponse to detecting an IAB broadcast, the IAB controller wirelesslyexchanges IAB attachment signaling with 5GNR access node 812 over radiocircuitry 861 and establishes a wireless IAB link with 5GNR access node812 over radio circuitry 861.

FIG. 9 illustrates the operation of 5G wireless network 800 to use IABto recover from 5GNR access node faults. When the fault occurs in 5GNRaccess node 411, the fault recovery application directs the IABcontroller to establish an IAB link. The IAB controller configures theRRC, SDAP, PDCP, RLC, MAC, and PHY in CU 870 and DU 860 to handle IABattachment and IAB links. The IAB controller in 5GNR node 811 detectsthe IAB broadcast from 5GNR access node 812 over radio circuitry 861 andthe RRC, PDCP, RLC, MAC, and PHY. The IAB controller in 5GNR node 811exchanges IAB attachment signaling with the IAB controller in 5GNR node812 over their RRCs, PDCPs, RLCs, MACs, and PHYs. The IAB controller in5GNR node 811 and the IAB controller in 5GNR node 812 establish awireless IAB link over their RRCs, SDAPs, PDCPs, RLCs, MACs, and PHYs.The IAB controller in 5GNR node 812 couples the IAB link to the NET CNTin 5G core NFVI 420 over the UPF or AMF. The NET CNT and the faultrecovery application use the IAB link to exchange fault data and recoverfrom the fault.

The wireless data network circuitry described above comprises computerhardware and software that form special-purpose network circuitry torecover from wireless access node faults using IAB. The computerhardware comprises processing circuitry like CPUs, DSPs, GPUs,transceivers, bus circuitry, and memory. To form these computer hardwarestructures, semiconductors like silicon or germanium are positively andnegatively doped to form transistors. The doping comprises ions likeboron or phosphorus that are embedded within the semiconductor material.The transistors and other electronic structures like capacitors andresistors are arranged and metallically connected within thesemiconductor to form devices like logic circuitry and storageregisters. The logic circuitry and storage registers are arranged toform larger structures like control units, logic units, andRandom-Access Memory (RAM). In turn, the control units, logic units, andRAM are metallically connected to form CPUs, DSPs, GPUs, transceivers,bus circuitry, and memory.

In the computer hardware, the control units drive data between the RAMand the logic units, and the logic units operate on the data. Thecontrol units also drive interactions with external memory like flashdrives, disk drives, and the like. The computer hardware executesmachine-level software to control and move data by driving machine-levelinputs like voltages and currents to the control units, logic units, andRAM. The machine-level software is typically compiled from higher-levelsoftware programs. The higher-level software programs comprise operatingsystems, utilities, user applications, and the like. Both thehigher-level software programs and their compiled machine-level softwareare stored in memory and retrieved for compilation and execution. Onpower-up, the computer hardware automatically executesphysically-embedded machine-level software that drives the compilationand execution of the other computer software components which thenassert control. Due to this automated execution, the presence of thehigher-level software in memory physically changes the structure of thecomputer hardware machines into special-purpose network circuitry torecover from wireless access node faults using IAB.

The above description and associated figures teach the best mode of theinvention. The following claims specify the scope of the invention. Notethat some aspects of the best mode may not fall within the scope of theinvention as specified by the claims. Those skilled in the art willappreciate that the features described above can be combined in variousways to form multiple variations of the invention. Thus, the inventionis not limited to the specific embodiments described above, but only bythe following claims and their equivalents.

What is claimed is:
 1. A method of operating a wireless access node torecover from a fault, the method comprising: a radio wirelesslyexchanging user data with wireless user devices; a baseband unit (BBU)exchanging the user data with a wireless communication network; the BBUdetecting the fault and responsively directing an Integrated Access andBackhaul (IAB) Mobile Terminal (MT) to scan for a wireless IAB service;the IAB MT scanning for the wireless IAB service; the BBU exchangingfault data with the IAB MT; the IAB MT wirelessly exchanging the faultdata with a neighbor access node over the wireless IAB service; the BBUrecovering from the fault in response to the fault data; the radiowirelessly exchanging additional user data with wireless user devices;and the BBU exchanging the additional user data with the wirelesscommunication network.
 2. The method of claim 1 wherein the BBUdirecting the IAB MT to scan for the wireless IAB service comprises aRadio Resource Control (RRC) indicating the fault to a fault recoveryapplication and the fault recovery application signaling the IAB MT toestablish an IAB link for the wireless IAB service.
 3. The method ofclaim 1 wherein the IAB MT scanning for the wireless IAB servicecomprises the IAB MT processing a list of IAB frequencies andresponsively detecting an IAB broadcast for the wireless IAB servicefrom the neighbor access node at one of the IAB frequencies.
 4. Themethod of claim 1 wherein the IAB MT wirelessly exchanging the faultdata with the neighbor access node over the wireless IAB servicecomprises exchanging Fifth Generation New Radio (5GNR) signals with theneighbor access node.
 5. The method of claim 1 wherein the IAB MT is ina Fifth Generation New Radio (5GNR) Distributed Unit (DU).
 6. The methodof claim 1 wherein the IAB MT is in a Fifth Generation New Radio (5GNR)Centralized Unit (CU).
 7. The method of claim 1 wherein the IAB MT is ina Fifth Generation New Radio (5GNR) Distributed Unit (DU) and the BBU isin a 5GNR Centralized Unit (CU).
 8. The method of claim 1 wherein theIAB MT is in a Fifth Generation New Radio (5GNR) Distributed Unit (DU)and the BBU is in the 5GNR DU.
 9. The method of claim 1 wherein the BBUrecovering from the fault comprises rebooting an Internet Protocol (IP)router responsive to the signaling.
 10. The method of claim 1 whereinthe BBU recovering from the fault comprises rebooting an ethernet switchresponsive to the signaling.
 11. A wireless access node to recover froma fault, the wireless access node comprising: a radio wirelesslyconfigured to exchange user data with wireless user devices; a basebandunit (BBU) configured to exchange the user data with a wirelesscommunication network; the BBU configured to detect the fault andresponsively direct an Integrated Access and Backhaul (IAB) MobileTerminal (MT) to scan for a wireless IAB service; the IAB MT configuredto scan for the wireless IAB service; the BBU configured to exchangefault data with the IAB MT; the IAB MT configured to wirelessly exchangethe fault data with a neighbor access node over the wireless IABservice; the BBU configured to recover from the fault in response to thefault data; the radio configured to wirelessly exchange additional userdata with wireless user devices; and the BBU configured to exchange theadditional user data with the wireless communication network.
 12. Thewireless access node of claim 11 wherein the BBU comprises a RadioResource Control (RRC) configured to indicate the fault to a faultrecovery application and the fault recovery application configured tosignal the IAB MT to establish an IAB link for the wireless IAB service.13. The wireless access node of claim 11 wherein the IAB MT isconfigured to process a list of IAB frequencies and responsively detectan IAB broadcast for the wireless IAB service from the neighbor accessnode at one of the IAB frequencies.
 14. The wireless access node ofclaim 11 wherein the IAB MT is configured to exchange Fifth GenerationNew Radio (5GNR) signals with the neighbor access node.
 15. The wirelessaccess node of claim 11 wherein the IAB MT is in a Fifth Generation NewRadio (5GNR) Distributed Unit (DU).
 16. The wireless access node ofclaim 11 wherein the IAB MT is in a Fifth Generation New Radio (5GNR)Centralized Unit (CU).
 17. The wireless access node of claim 11 whereinthe IAB MT is in a Fifth Generation New Radio (5GNR) Distributed Unit(DU) and the BBU is in a 5GNR Centralized Unit (CU).
 18. The wirelessaccess node of claim 11 wherein the IAB MT is in a Fifth Generation NewRadio (5GNR) Distributed Unit (DU) and the BBU is in the 5GNR DU. 19.The wireless access node of claim 11 wherein the BBU is configured torecover from the fault by rebooting an Internet Protocol (IP) routerresponsive to the signaling.
 20. The wireless access node of claim 11wherein the BBU is configured to recover from the fault by rebooting anethernet switch responsive to the signaling.